The British & Irish Lions Test star had initially returned to the Scarlets line up for their LV= Cup clash with London Irish on February 1 but Gatland opted against rushing him back into the side to face Ireland or France, with Scott Williams starting in Dublin and George North switching to the midfield last time out.
Davies then sat out the Scarlets' narrow success against Edinburgh a day after Wales saw off the French but Jones says that his showing on Sunday will have been a major boost to the national set up prior to the crucial clash at Twickenham.
"Jon's performance was pretty good considering the length of time he has been out and the lack of rugby he has played," said Jones, who was Wales backs coach when they retained the Six Nations title last season.
"He's a perfectionist, so he will never be happy with his performance. But he has shown he is fit and, with his first carry of the game, that he has not lost any of that line breaking ability.
"He will give Wales a boost when he returns back for duty. Thankfully, I'm back with the Scarlets now, so I don't have to make the decision because it will be a difficult decision to make.
"Whatever backline Wales put out next weekend it will be a good one. George (North) did a good job, particularly in attack against France, and Liam (Williams) was good on the wing.
"But having Jon Davies coming back into the equation is not a bad thing. The thing with those players is they can give you different types of attacking options - they challenge the gain line, offload in the tackle and Jon's distribution is good as well."